engleski

Influence of hyperreductive (oxygen free) pressing on content of hydroxycinnamic acids in must and wine of variety Malvasia istriana

Hydroxycinnamic acids (HCA) are the major phenols localized in grape juice and therefore the major phenols in white wine. Representative hydroxycinnamic acids in grape and wine are esters with tartaric acid: caftaric acid, coutaric acid and fertaric acid. Hydroxycinnamic acids have antioxidant properties and as such they could impact the wine sensory characteristics as well they could have positive effects on human health. Hyperreductive (low oxygen concentration) pressing of white grapes is already in use in certain wineries ; however their influence on Malvasia istriana has never been studied. In our research, we performed small scale oxygen free pressing of Malvasia istriana grape. The concentration of oxygen in the press was below 1%. The profile of hydroxycinnamic acids was analysed in must after pressing, after sedimentation and in white wine after fermentation. Our results showed that pressing Malvasia istriana grapes in hyperreductive conditions greatly influences the concentration of hydroxycinnamic acids. The concentration of caftaric acid in wines pressed in hyperreductive conditions was 207% higher then in wines when grape was pressed in a presence of oxygen (normal pressing conditions). The concentration of coutaric acid was 8% higher in hyperreductive comparing normal pressing conditions. On the other hand grape reaction product (GRP) which rises in the case of must oxidation, was 52% lower in wines pressed under hyperreductive conditions. It was shown that hyperreductive conditions in Malvasia istriana grape pressing could increase the content of hydroxycinnamic acids in wine which might impact also the sensory properties of Malvasia istriana.

antioxidants; hydroxycinnamic acids; white wines; oxygen; cv. Malvasia istriana

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